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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5334_Библиотеки_им_академика_М_И_Перельмана
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dehydrated) or decreased (e.g., for patients with renal failure or congestive
heart failure). A daily requirement of between 2 and 3 L per day is usual for
adults.
1. Calculate the daily fluid requirement range for a patient weighing 162
lb
Note: This volume range would be rounded to 2200 to 2600 mL/day in
practice.
2. Calculate the daily fluid requirement for a patient who is 5 feet 2 inches
tall and weighs 114 lb. Use the equation in Chapter 8 to determine
BSA.
Caloric requirements
The kilocalorie (kcal) is the unit used in metabolism studies. By definition,
the kilocalorie (or large Calorie, C, or Cal.) is the amount of heat required to
raise the temperature of 1 kg of water by 1°C. The caloric requirements for
patients vary, depending on their physical state and medical condition. The
Harris-Benedict equations,17 which follow, are commonly used to estimate
the daily basal energy expenditure (BEE) requirements for nonprotein
calories. The BEE is also referred to as the resting metabolic energy (RME)
or the resting energy expenditure (REE).
For males:
For females:
The total daily expenditure (TDE) of energy, as calculated, may be adjusted
for activity and stress factors5,10:
As an alternative to the use of the Harris-Benedict equations, clinicians can
estimate the BEE for adults as 20 to 25 kcal/kg/day for otherwise healthy
patients with mild illness, 25 to 30 kcal/kg/day for nonobese patients with
moderate illness, and 30 kcal/kg/day or greater for severely burned
patients.5 Energy requirements for infants, children, and teenagers are
different from those for adults and vary according to age, growth rate, and
clinical/metabolic status.
1. Using the Harris-Benedict equation, calculate the BEE for a 78-year-
old male patient, measuring 5 feet 8 inches in height and weighing 160
lb.
2. Calculate the TDE for the patient in example problem 1 factoring in an
activity factor of 1.2 (confined to bed) and a stress factor of 1.2
(surgery).
3. Calculate the BEE for the above patient using the alternative method of
25 kcal/kg/day.
Note: The weight of the patient in kilograms shown here is rounded to
two decimal places; however, in the calculation the weight should not
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be rounded as reflected in the answer to the problem.
Carbohydrate requirements
Carbohydrates are the primary source of cellular energy. In formulas for
parenteral nutrition, dextrose provides 3.4 kcal of energy per gram; for
example, each 100 mL of a 25% dextrose injection provides 85 kcal of
energy. For enteral nutrition, the factor used is 4 kcal/g.
Protein requirements
In TPN, protein is provided as amino acids. The purpose of the protein
support is not to produce energy, although energy is produced by proteins by
a factor of 4 kcal/g, but rather to build tissues and body strength.
15
Therefore, a patient’s caloric needs should be provided by nonprotein
calories, and the contribution of protein calories to the daily expenditure is
optional and may be omitted. The daily quantity of protein required in
adults is generally estimated to be5:
0.8 g/kg/day in an unstressed patient
1 to 1.5 g/kg/day for most patients over 60 years old
1.5 to 2 g/kg/day for a patient with a critical illness, infection, or
trauma
0.5 g/kg/day for a patient with liver failure
Lipid (fat) requirements
Lipids may be used to provide energy when the body cannot obtain all the
necessary energy requirement from carbohydrates. The proportion of
calories provided by lipids is usually restricted to 20% to 40% of the total
daily calories. Lipids provide 9 kcal of energy per gram. Lipids are
generally administered parenterally in the form of an emulsion containing
carbohydrate-based emulsifying agents, which also contribute to the caloric
content. It has been determined that a 10% lipid emulsion provides 11 kcal/g
of total energy or 1.1 kcal/mL, and a 20% to 30% lipid emulsion provides
10 kcal/g of total energy (2 kcal/mL and 3 kcal/mL, respectively).12 The
abbreviation IVFE, for intravenous fat emulsion, is often used to indicate
the lipid component of a parenteral nutritional formula.
Fiber requirements
Dietary guidelines generally recommend a daily intake of 14 g of fiber for
each 1000 calories consumed. This translates to approximately 21 to 25 g of
daily fiber for women and between 30 and 38 g for men. Insoluble fiber
reaches the large intestine after ingestion and is associated with good bowel
function, whereas soluble fiber partially dissolves in the upper
gastrointestinal tract and is associated with reduced absorption of dietary fat
and cholesterol.
18
Electrolytes
As shown in Figure 14.2, the standard quantities of electrolytes may be used
or modified by the following parameter, or other.
6
Sodium 1 to 2 mEq/kg/day
Potassium 1 to 2 mEq/kg/day
Calcium 10 to 15 mEq/day
Magnesium 8 to 20 mEq/day
Phosphorus 20 to 40 mmol/day
Enteral and Parenteral Nutrition Calculations
Example calculations of enteral nutrition
The nutritional requirements for a 76-year-old male who is 6 feet 2 inches
tall and weighs 201 lb have been determined to be as follows:
Protein: 73.09 g/day
Lipids: 81.23 g/day
Carbohydrates: 266.34 g/day
Water: 2088.82 to 2740.91 mL/day
Total calories: 2088.82 kcal/day
A ready-to-drink nutritional liquid product is selected for this patient. A
one-quart container provides 37 g protein, 143 g carbohydrates, 37 g lipids,
and 1.06 kcal/mL.
a. How many milliliters of the product should this patient receive daily
to meet his caloric requirements?
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b. How many grams each of protein, carbohydrates, and lipids would
this volume provide?
c. If the product contains 85% free water, does it meet the patient’s daily
water requirement?
Therefore, the amount of water provided by 1970.58 mL of the
formula would not fully meet the patient’s daily water requirement.
d. If the formula is to be delivered continuously over a 24-hour period,
what would be the flow rate in mL/h?
e. If the patient is to continue receiving this formula at home by
intermittent feedings over 40 minutes every 4 hours, what volume
would be administered with each feeding, and what would be the
flow rate in mL/h?
Example calculations of parenteral nutrition
The following basic steps may be used as a guide in TPN calculations:
STEP 1. Calculate the TDE required using the Harris-Benedict equations,
and apply the appropriate stress or activity factors.
STEP 2. Calculate the daily quantity (g) of amino acids (protein) required
based on 0.8 g/kg of body weight, or use one of the other values listed
on page 283 to accommodate for various disease states.
STEP 3. Calculate the number of calories supplied by the amino acids
(from STEP 2) at 4 kcal/g. This step may be omitted if protein calories
are not included in the TDE.
STEP 4. Calculate the kcal of lipids required at 20% to 40% of the TDE.
STEP 5. Calculate the volume of lipid emulsion required (from STEP 4)
based on 1.1 kcal/mL (10% lipid emulsion), 2 kcal/mL (20% lipid
emulsion), or 3 kcal/mL (30% lipid emulsion).
STEP 6. Calculate the quantity of carbohydrate required based on 3.4
kcal/g after accounting for the contribution of the lipids (and amino
acids if included).
STEP 7. Calculate the daily fluid requirement using 30 to 35 mL/kg/day or
one of the other methods described earlier in the text.
NOTES: In some clinical practices, (a) a patient’s actual body weight, the
ideal body weight, or adjusted body weight may be used in the calculations
(in STEP 1); and (b) in STEP 6, the energy provided by the protein, in addition
to that from lipids, may or may not be taken into account. In addition to
STEPS 1 through 7, TPN calculations also can include:
Determination of the quantities of the pharmaceutical sources of the
macronutrients (e.g., LVPs) and micronutrients (e.g., vials) to use to
obtain the required components
Determination of the total TPN volume, the number of TPN bags to be
prepared, and the rate of flow
1. Calculate the parenteral nutrition and fluid requirements for a 58-year-
old woman who is 5 feet 3 inches tall and weighs 140 lb. She is
ambulatory (activity factor = 1.3) and has undergone surgery (stress
factor = 1.2). The solutions to be used for the macronutrients are 8.5%
w/v amino acid solution, 20% w/v lipid emulsion, and 70% w/v
dextrose solution.
STEP 1. Total daily kcal required by Harris-Benedict equation:
STEP 2. Protein required (grams):
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STEP 3. Protein (kcal):
STEP 4. Lipids required (kcal), using 30% of TDE:
STEP 5. Lipids required (mL), using a 20% lipid emulsion:
STEP 6. Carbohydrates (dextrose) required (grams), accounting for kcal
from both protein and lipids:
STEP 7. Fluid required (milliliters):
Based on 30 mL/kg/day:
Based on 1 mL/kcal required/day:
Total volume provided by macronutrient solutions:
598.93 mL/day (protein) + 301.41 mL/day (lipids) + 505.43 mL/day
(dextrose) = 1405.77 mL/day
The patient should receive 598.93 mL of 8.5% amino acid solution,
301.41 mL of 20% lipid emulsion, 505.43 mL of 70% dextrose
solution, and approximately 500 mL of additional fluids per day.
2. The following is a formula for a desired parenteral nutrition solution.
Using the source of each drug as indicated, calculate the amount of
each component required in preparing the solution.
To be added to:
Amino acid infusion (8.5%) 500 mL
Dextrose injection (50%) 500 mL
a.
b.
c.
d.
e.
f.
g. 10 mL
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3. The formula for a TPN solution calls for the addition of 2.7 mEq of
Ca2+ and 20 mEq of K+ per liter. How many milliliters of an injection
containing 20 mg of calcium chloride dihydrate per milliliter and how
many milliliters of a 15% (w/v) potassium chloride injection should be
used to provide the desired additives?
4. A potassium phosphate injection contains a mixture of 224 mg of
monobasic potassium phosphate (KH2PO4) and 236 mg of dibasic
potassium phosphate (K2HPO4) per milliliter. If 10 mL of the injection
are added to a TPN solution containing 500 mL each of 7% amino acid
solution and D10W (10% dextrose in water for injection), (a) how
many milliequivalents of K+ and (b) how many millimoles of total
phosphate are represented in the prepared solution?
a.
b.
CASE IN POINT 14.1
A hospital pharmacist is asked to provide TPN for a 75-year-old female
patient who is 5 feet 2 inches in height and weighs 120 lb. The patient is
confined to bed but has no stress factors. The pharmacist reviews the
patient’s laboratory records and based on experience decides to prepare a
2000-mL TPN, utilizing a 10% amino acid injection as the protein
source, D50W as the source of dextrose, and a 20% lipid emulsion as the
fat source, with a standard mixture of electrolytes, minerals, and
vitamins. The pharmacist asks a student on a pharmacy practice
experience program to perform these basic calculations:
a. Target amount of the patient’s daily fluid requirement
b. Target amount of daily protein requirements (g/day)
c. Volume of amino acid injection that may be required
d. Target amount of nonprotein calories (kcal)
e. The volume of D50W that could supply the nonprotein calories
The Nutrition Label
The Dietary Guidelines for Americans 2015–2020,19 issued by the U.S.
Department of Agriculture (USDA) and Health and Human Services (HHS),
provide guidance aimed at improving health and reversing obesity and
related diseases. The document includes basic nutritional information and
dietary recommendations, while the web site offers interactive tools to assist
consumers in meeting dietary objectives. In March 2018, the FDA
announced its Nutrition Innovation Strategy to review and produce
measures in preventing death and disease related to poor nutrition.20 The
familiar “Nutrition Facts” label (Fig. 14.3) that accompanies packaged
foods is a labeling requirement of the FDA and provides direct guidance to
the consumer.19,21,22 This label was updated to reflect changes in the new
guidelines and recommendations. Through knowledge of dietary
requirements and the nutrition label, pharmacists have a unique opportunity
to counsel patients.
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